Renewable fuse



Se t. 39, 1933. c. E ov KRIEGSTEDT 1,927,359

asmwaaw FUSE Filed Sept. 12, 1930 I N VEN TOR.

| fl'EOKR/EGSTEDT,

BY J27. ATTORNEY.

Patented Sept. '19, 1933 RENEWABLE FUSE Carl E. O. Kriegstedt,

Washington, D. 0., as-

signor, by mesne assignments, to The Engineering Appliance Corporation, a corporation of Delaware Application September 12, 1930 Serial No. 481,555

11 Claims.

This invention relates to electric fuses, and has particular reference to fuse plugs or cartridge fuses having means for permitting the renewal of the fusing element, thereby enabling the fuse to be used indefinitely.

A very important object of the invention is the provision of visual signalling means, operable upon the burning of the fuse element, to thereby distinguish the burned fuse from the others.

Much annoyance has been occasioned by the' burning or blowing of a fuse at night, thereby requiring a search with matches, or other lighting equipment, and the necessity of removing each fuse and testing with a good one to determine the faulty one. With the type of fuse hereinafter described, a visual signal is displayed in the form of a miniature glow lamp, the illumination of which depends upon the blowing of the fuse, and will readily direct the attention of the searcher to the plug having the burned fuse.

A further object is the extreme simplicity of the device, and the ease with which a new fuse element can be inserted, requiring but the fraction of a minute to remove the burned fuse element and insert a new one. Further, the low cost of the fuse elements makes this plug much more desirable, aside from the very important feature of the visual signal.

Other important objects and advantages of the 80 invention will be apparent during the course of the following description.

Referring to the drawing:

Figure 1 is a side elevation of a fuse plug constructed in accordance with the invention,

Figure 2 is a central vertical section thereof,

Figure 3 is a bottom plan view thereof,

Figure 4 is a similar view with parts removed,

Figure 5 is a' perspective view of a fuse employed,

4 Figure 6 is a side elevation of a modified form of the invention,

Figure 7 is a right hand end view,

Figure 8 is a left hand end view,

Figure 9 is a central longitudinal section thereof,

5 Figure 10 is a transverse section taken on line formed in the body 12 are the elements of an incandescent lamp 13. Whereas I have herein shownand described the miniature glow lamp or incandescent bulb 13 as having a filament 14 and lead wires 15 and 16, it is, of course, to be understood that any other kind of glow lamp of the incandescent type may be employed. The lead wire 15, see Figure 2, has permanent welded connection with the shell 11, as shown, while the wire 16 has permanent welded or soldered connection 5 [with a centrally disposed plug 17, the enlarged head of which is permanently set in the body 12, while the shank thereof extends for a substantial distance below the body and has its end provided with screw threads 18.

The numeral 19 designates an insulating disc, having formed therein a pair of diametrically oppositely arranged arcuate slots 20, see Figures 2 and 4. One of the slots 20 is adapted to receive a tongue extension 21, integral with the shell 11, and having its end bent outwardly against the lower face of the disc 19. The opposite slot 20 is for the reception of a lead extension 22, the lower end of which is, likewise, bent outwardly against the lower face of the disc 30 19, while its opposite end is permanently connected with the enlarged head of the plug 1'7, and embedded within the body 12. The disc is provided with a central opening 23, for the passage of the plug 17. It will, therefore, be seen 35 that the bending of the members 21 and 22 will securely hold the disc against the lower face of thebody, while, at the same time, providing a pair of exposed contacts below the disc.

' The numeral 24 designates a fuse retaining cap of cuplike formation and having a central screwthreaded opening 25, adapted to engage the end 18 of the plug 17. A ring fuse member 26 is adapted to be placed within the cap 24 and the cap screwed in place to cause the fuse 26 to firmly make contact with the members 21 and 22. The fuse 26 is formed of any suitable fusible metal adapted to fuse under abnormal loads.

In the use of this form of the invention, the

plug as a whole, is screwed into the conventional through wire 15, filament 14, wire 16 to the plug 110 Assuming now that an abnormal load reception of plugs and "vided with an enlarged 17, causing the filament to glow and quickly direct attention to the failure of the fuse 26. In order to renew the fuse 26, it is only necessary to unscrew cap 24, shake out old parts of the fuse, and insert a new one and replace the cap. Cap 24 is provided with a plurality of gas escape openings 24.

It will, therefore, be obvious from the foregoing that the fuse plug will continue to function indefinitely, or so long as the filament 14 continues to glow. However, aside from the signalling element, the plug could be used indefinitely by merely renewing the fuse rings 26. In this case, however, it would be necessary to inspect the plug 'to determine its condition.

Referring now to Figures 6 to 11, inclusive, wherein is illustrated a cartridge type of fuse operating in a similar manner to the fuse plug. In this form of the invention, the numeral 2'? designates a glass tube having ferrules 28 and 29, rigidly mounted on its opposite ends and projecting therebeyond. ,The projecting portions of the ferrules are internally screw-threaded for the 31. The plug 30 is proknurled head 32 to aid in removing it. The plug 30 has a reduced portion 33, forming a shoulder 34, adapted to support a fusible member 35, similar to the member 26. The shoulder 34 serves to support the fuse 35 against metallic contacts 36 and 37, carried by strips 38 and 39, in turn lying against the inner wall of the glass tube 27 and permanently attached to the ferrules 29 and 28, respectively.

The strip 38 is provided with a struck-out spring tongue 40, while the strip 39 has its free end bent at a right angle and extending substantially to the center of the tube. The numeral 41 designates a removable incandescent lamp, having a metallic base ring 42, and a central contact 43. The lamp is adapted to be held in place by the plug 31, having a curved inner recess to accommodate the end of the lamp.- When the lamp is in position, the spring tongue engages the ring 42, while the strip 39 engages the central contact 43. The plug 30 is provided with a central opening 44, extending entirely therethrough to permit the escape of gases created by the burning of the fuse.

Assuming now that the parts are in position shown, with the fuse 35 forced against the contacts 36 and 37, by the plug 30. Current will, therefore, flow from the ferrule 23 through strip 38, across fuse 33 to contact 37, strip 39 to ferrule 28 and thence to opposite pole of source of cur-- rent. Assuming now that the load on the line exceeds that for which the fuse 35 is made, current will attempt to flow as before described, but will immediately cause fuse 35 to burn, breaking connection between the strips 38 and 39. Current will then flow from ferrule 29, strip 38, tongue 40, ring 42, through filament of lamp 41 back to contact 43, strip 39 to ferrule 28, causing lamp 41 to become illuminated and direct attention to defective fuse.

It will be apparent, from the foregoing, that extremely simple and efficient fuses have been provided. The fuses are quickly renewed, and the signal feature will save a deal of time in locating and correcting blown fuses.

It is to be understood that the invention is not limited to the precise construction set forth, but that it includes within its purview whatever changes fairly come within either the terms or the spirit of the appended claims.

Having thus described my invention, what claim is:

1. A fuse plug of the character described, comprising a threaded shell and an insulating body formed therein, a cap detachably secured to one end of the body portion, ported by said cap, a glow lamp formed upon the end of the body portion opposite to said cap, and means for causing said lamp to glow upon the burning .of said fusible element.

2. A fuse plug formed of a body of insulatin material having an outer threaded metallic shell,

an insulating disc carried upon one end of thebody portion, a glow lamp permanently supported by said body portion upon its opposite end, a detachable cap for the lower end of the plug, a fusible element supported within said cap, and means operable upon the burning of said fusible element to cause said lamp to glow.

3. A fuse plug comprising a threaded shell and an insulating body molded therein, a glow lamp bulb rigidly supported in said molded body, a rigid terminal secured within said body portion centrally thereof and projecting therebelow, an insulating disc mounted upon the lower end of the body portion and supported thereon by an extension of said shell and an extension of said terminal, a cap removably supported by said terminal, a fusible element carried within said cap and engaging said shell extension and said terminal extension, said cap provided with vents, said lamp so connected with the several parts as to glow when the fusible element burns.

4v A fuse'plug having a body of insulating material and an outer metallic threaded shell, a glow lamp bulb supported in said body, a metallic terminal supported in said body centrally thereof and projecting substantially therebeyond, an insulating disc mounted upon the lower end of the plug and provided with an opening for the passage of said terminal, said disc provided with oppositely arranged arcuate slots, said shell provided with an extension adapted to engage within one of said slots with its free end out-turned, said terminal provided with an extension adapted to engage the other of said slots and having its free end outtu'rned, said terminal having its free end threaded, a cap threaded upon said terminal, a fusible element supported within said cap and engaging said outturned ends, vents formed in said cap, said lamp provided ,with a filament, having one lead connected to said shell and the other lead connected to said terminal, said lamp adapted to glow upon the burning of said fusible element.

5. A renewable fuse plug having a threaded body provided with a pair of terminals and a cap removably secured upon one end, a fuse supported within said cap and electrically connecting said terminals, said fuse formed of fusible metal in a flat ring formation.

6. A cartridge fuse formed of a body of transparent material having detachable plugs on each end, a glow lamp carried within saidbody and removable therefrom, said lamp being held in said body by one of said plugs, a fusible element supported within said body, said fusible element adapted to electrically connect the opposite ends of said body, means operable upon the burning of said fuse for causing said lamp to glow.

7. A cartridge fuse comprising a tubular body of transparent material having metallic ferrules on its ends, detachable plugs threaded in said ferrules, an incandescent lamp positioned within said tubular body and held therein by one of said a fusible element sup.

plugs, 4 metallic contacts carried by said ferrules and extending within said body, one of said plugs formed of insulating material and adapted to support a fusering, said fuse ring adapted to ention for supporting a ring fuse, said fuse when in position adapted .to engage portions of said metallic elements, said metallic elements having extended means, an incandescent lamp positioned within said tubular portion with its terminal end engaging said extensions, said insulated plug having a vent opening formed therethrough, said lamp held in engagement with said extensions by the other of said plugs, said lamp through the medium of said extensions caused to glow upon the burning of said fuse.

9. Afuse ofthe character described compris-' ing a body portion having a threaded shell, a glow lamp permanently attached to' said body portion,

said body portion having a recess therein, means for separating the recess from said lamp, 9. fusible element, a holder having detachable connection with the fuse body for removably supporting said fusible element within said recess and said lamp adapted to glow upon the burning of said fusible element;

10. A plug fuse device comprising-a body having a threaded shell and tip contact terminals. means permanently carried by said body and connected across said terminals for visually indicating the rupture of a fusible element, a renewable fuse element insertable within said body and connected across said terminals thereby normally short circuiting said means and means detachably connected to said body for removably supporting said fuse element therein.

11. A plug fuse device comprising a body having a recess'at the rear end thereof, a fuse adapted to be inserted in said recess, means detachably connected to said body for removably supporting said fuse in operative position in said recess, and electrical means permanently attached to the forward end of said body and connected in shunt with said fuse for visually indicating the rupture of the fusible element of said fuse.

cam. o. mos'mn'r; 

